Small steam generators have found application in many fields. These steam generators are usually electric powered and provide steam for cooking and sterilizing functions. Frequently the steam boilers are an integral part of such sterilizing or cooking ovens and may therefore be generally inaccessible once the cooking or sterilizing apparatus has been placed into service. These small steam generators suffer from the same problems that larger generators have, in that whenever water is heated or boiled, the natural consequence is the build-up of a residue. The residue derives from the fact that water contains many dissolved minerals which upon heating causes them to precipitate and bond to the inner boiler surfaces. This bonded material is commonly referred to in the industry as scale; consequently, descaling becomes a regular part of boiler maintenance. The scale itself, if not removed on a regular basis, can build up to the point where it can significantly reduce the boiler efficiency in addition to blocking drains and valves and even causing heater failure in electric powered steam boilers.
Steps can be taken to purify the water prior to its introduction into the steam generator but frequently these purification techniques prove to be troublesome, expensive and ineffective. An alternative is to descale the boiler at regular intervals during its operational cycles. Frequently, complete descaling of a boiler becomes time consuming, expensive and overly burdensome if done on a daily or even a weekly basis. In response, boiler operators have come to adopt an abbreviated type of descaling which is referred to as blowdown. This blowdown procedure simply involves switching the boiler off-line, filling the boiler and allowing it to pressurize and then opening an exit valve to allow the water and steam to quickly escape carrying with it entrained loosened particles of scale.
When the descaling procedure is put into practice the boiler is taken off line, filled with a cleaning solution, generally water and a strong acid, such as phosphoric acid, which cleaning solution is boiled in the boiler chamber itself. The tumbling boiling action of the strong acid solution chemically attacks and simultaneously dislodges and dissolves scale from the boiler interior. The solution is then driven from the boiler by steam pressure similar to the technique used in blowdown cleaning and the boiler is then flushed one or more times before being placed back on line.
The blowdown technique is not in and of itself effective over a long period of time. Consequently it follows that a boiler cleaner system capable of performing either a blowdown cycle or a descaling cycle would be ideal to meet the needs of the industry.